Fallon noted that the next time he sees Trump, he could be the President of the United States, so he asked if he could do something "not presidential."

"Can I mess your hair up?" Fallon asked, to raucous applause and cheers from the audience.

Trump agreed!

Watch the hilarious moment above.

Trump joined Maria Bartiromo this morning on Fox Business Network, where he was asked about the memorable moment.

He said the video proves "my hair is my hair" and should put to rest any theories to the contrary.

Following his interview Thursday with Dr. Oz, where he discussed his health, Trump said he feels like he's 35 years old.

"I don't think I'm 35, but I feel the same in terms of my health as if I'm 35," explaining the grueling schedule he has kept during the campaign and arguing that it's "much more vigorous" than Hillary Clinton's.

Latest from Fox News Channel

House Intelligence Committee Chairman Adam Schiff of California said that "people have suffered enough" because of President Trump and that a real leader would re-open the part of the government that has been shuttered since December.